The purpose of this contract is to acquire on a fixed-price, indefinite quantity basis, through the issuance of separate task orders, PILOTplus support programming and any related services necessary to develop PC Learn Packages. PC Learn Packages are computer-assisted instruction packages developed for use on a PC. PC Learn Packages for CHEMLINE, ELHILL, and MEDLINE will be the first tasks issued under this contract. The CHEMLINE Learn Package will describe the CAS Registry Number, Synonyms, CAS Type 1 Name, Molecular Formula and Locator fields in CHEMLINE. It will discuss the ring information fields contained in CHEMLINE. It will contain simulated searches such as a Registry Number search, a chemical name search, a name fragment search, molecular formula search, a substructure search, and a CHEMLINE/TOXLINE search. The ELHILL Learn Package will describe the basic commands and search capabilities of the ELHILL software as they pertain to the CHEMLINE and TOXLINE files. The Learn package will describe the logon-logoff procedures, search statements and commands, qualification, logical operators, the NEIGHBOR and FIND commands, the PRINT commands and its options, variable character replacement symbols, multi-meaning messages, and the use of ALL. The MEDLINE Learn Package will describe the author, title, abstract, Medical Subject Headings (MeSH), source, year of publication, language, and other search limiters in MEDLINE. It will introduce the concepts of subject searching using MeSH and Text Words as well as author searching. Simulated searches will be included and should comprise author and subject searching, Boolean logic, search limiting, some print commands, and various other basic operating commands as may be needed for adequate coverage of MEDLINE searching.